Recently, the printed image typified by photographic image and poster is formed by an ink-jet apparatus or an electrophotographic image forming apparatus additionally to usual silver halide photographic system and gravure printing method.
For instance, formation of an fine dot image on a level of 1200 dpi (dpi: dot number per inch (2.54 cm)) is made possible in the field of the image forming technology of electrophotography such as copying machine or printer accompanied with the progress in the technology such as digitalization of exposing system and minimizing of the toner diameter.
Moreover, a technology capable of forming a full color image is developed in which toner images are respectively formed on plural photoreceptor drums and the formed toner images are piled by primarily transferred onto an intermediate transferring member, and the image formed on the intermediate transferring member is secondarily transferred onto an image supporting member. As above-mentioned, the formation of full color image requiring high resolving power such as that of the photographic image can be realized by such the image forming method additionally to the usual silver halide photography or printing technology.
A glossy image is often required in a photographic image of poster, however, white background area with low glossiness of the image formed by the toner is obtained sometimes even though the images area fixed on the support such as a paper sheet has some degree of glossiness. Such the unbalance in the glossiness in the finished image causes degradation in the quality of the printed matter, therefore countermeasure to such the phenomenon is demanded.
On such the background, a technique is investigated, by which the image formation is carried out by using a toner constituted by omitting colorant from the usual color toner, so called as a transparent toner or transparent toner, for preventing the formation of ununiformity in the glossiness on the image. In concrete, a technique is disclosed, in which the transparent toner is uniformly provided on the whole surface of the support carrying the image and heated and cooled to form a transparent toner layer on the whole surface of the image for preparing a printed matter having uniform glossiness on the whole surface of the image; cf. Patent Document 1, for example. Moreover, a technique is disclosed in which a transparent toner layer is formed on the image formed by a printer by using a glossing apparatus to provide a glossy printed matter; of Patent Documents 2 and 3, for example.
Such the apparatus is connected with a printer such as an electrophotographic printer and the transparent toner layer is entirely formed on the surface of the image formed by the printer, and the transparent toner layer is melted by heating the layer in a state of contacting with a belt. And then the transparent toner layer is solidified by cooling while contacting with the belt. The printed matter is naturally released from the belt after solidifying of the transparent toner layer; thus the glossy printed matter is finished.
Furthermore, a full color image forming technique is known, in which difference of the physical properties between the image forming toner and the transparent toner is noted and the difference between the particle diameter of the colored toner and that of the transparent toner is specified to obtaining the uniform glossiness; cf. Patent Document 4, for example. A glossy surface having smoothness at a level on which an image can be mirrored by light on the surface can be obtained by such the techniques so that high quality glossy printed matters can be provided on the market.
In the technique disclosed in Patent Documents 2 and 3, however, the belt is gradually degraded by repeating the glossy surface formation since the heating and cooling are always carried out while contacting with the surface on which the transparent toner is provided. Cracks or flaws are caused on the belt surface accompanied with the degradation thereof. As a result of that, the irregularity of the belt surface such as the cracks and flaws is transferred onto the glossy surface of the image so that any uniform glossy surface without unevenness cannot be obtained when the degraded belt is used for forming the glossy surface.    Patent Document 1: JP-AH11-7174    Patent Document 2: JP-A2002-341619    Patent Document 3: JP-A2004-258537    Patent Document 4: JP-A2007-140037